The tertiary value, name,
is the "name" of function.
The name is intended for debugging only and is not necessarily one that would
be valid for use as a name in defun or function, for example.
By convention, nil is used to mean that function has no name.
Any implementation may legitimately return nil
as the name of any function.

Examples:

The following examples illustrate some possible return values, but
are not intended to be exhaustive: